Refrigeration Product Cooling and Freezing Load Calculator
Sizing a blast freezer or chiller starts with the heat in the product. This calculator adds sensible heat above and below freezing and the latent heat of freezing, then converts to kW and tons of refrigeration.
Your numbers
Must be above the freezing point.
Around -1 to -2 C for meat and many produce items.
About 335 kJ/kg times water fraction times frozen share.
Fans, defrost, door openings, infiltration.
Your results
Product properties vary widely by composition and packaging. Use measured or published values for your product. Excludes room envelope, lighting and equipment loads, which a refrigeration engineer must add.
Refrigeration load (kW) vs process time
Sweeps Process time from 2 to 48, holding your other inputs fixed.
Link energy use to production orders
An optional look at tying freezer energy data to batch output in your ERP.
Optional. The tool and every export work without this. No spam.
How to use it
Enter product mass per batch, entering and final temperatures, the initial freezing point and specific heats. For chilling only, set the final temperature just below the freezing point and latent heat to zero. Choose the process time you need to reach core temperature. The result is the average load; peak load at pull-down is higher.
- Latent heat depends on water content
- Use core, not surface, temperature
- Add room and equipment loads separately
The equations
Heat above freezing is mass times specific heat times the drop to the freezing point. Latent heat is mass times latent heat of freezing. Heat below freezing is mass times the frozen specific heat times the drop from freezing point to final temperature. Divide kilojoules by seconds to get kW. One ton of refrigeration is 3.517 kW. This is the ASHRAE-style product load before system factors.
Example and cautions
Freezing 2,000 kg from 10 C to minus 18 C in 8 hours: sensible above is about 78,200 kJ, latent about 440,000 kJ, below about 63,000 kJ, total about 581,000 kJ. Over 8 hours that is about 20 kW, or about 23 kW with a 1.15 factor, near 6.5 tons. Cautions: pull-down loads in the first hours are higher, and packaging, pallets and trolleys add heat.
Frequently Asked Questions
What is the latent heat of freezing for food?
Pure water is about 335 kJ per kg. For food multiply by water content and by the fraction of water frozen. Lean meat, around 75 percent water and mostly frozen, is roughly 220 to 250 kJ per kg.
Why is the freezing point not 0 C?
Dissolved solutes lower it. Most meats freeze near minus 1 to minus 2 C, and sugary products much lower.
Is the answer peak or average load?
It is the average load over the chosen time. Heat removal is front-loaded, so size equipment with the pull-down peak in mind.
What is a ton of refrigeration?
A ton of refrigeration is 12,000 BTU per hour, which equals 3.517 kW of heat removal.
Energy meters, batch weights and run times usually sit in different systems. Netray can combine them into one read-only analysis on your own infrastructure.
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